1. Field of the Invention
This disclosure relates generally to X-ray imaging systems, more particularly to, method and system for maintaining iso-center constant while moving from one area of interest to another in an iso centric X-ray imaging system.
2. Description of the Prior Art
In an iso-centric X-ray imaging system, iso-center is defined to be a point in three dimensional space, where the center rays of the X-ray devices meet. The iso-center point is defined with reference to FIG. 1.
When a patient table is tilted, the iso-center point has to be kept constant. Currently, while tilting the patient table, all other axes motions are locked internally, so that the iso-center point is not lost and is kept constant. To keep the iso-center constant, during table tilt motion, the gantry is moved simultaneously. The iso-center is tracked continuously, and is kept a X-ray exposure as constant. This is called incidence keeping.
During an imaging procedure, it is required that the area of interest or focus has to be changed from one region or part of the body to another. During this time, the iso-center has to be shifted with reference to the new area of interest. For example, if the contrast agent flows quickly/slowly during a procedure, the area of interest may need to be shifted. Since there is no possibility of dynamically shifting iso-centers based on the new area of interest, it results in the following problems.
To focus on another area of interest, an operator/user/radiologist must come out of the current incidence keeping mode, position the gantry and the table in such a way that the new area of interest is in focus, and again start the incidence keeping. This requires excessive X-ray exposure to reach the intended area of interest and a considerable amount of time and effort.
Further, an operator/user/radiologist does not have instant access to the other axes of the system, to change the area of interest, as all the other axes are locked. This results in a lengthy workflow, wherein, there's a necessity to come out of the incidence keeping mode, manually position the table and/or the gantry to the required area of interest, and then go back to incidence keeping mode.
Thus, it would be beneficial to have a method and system for tracking the iso-center even while changing the area of interest.